Electric furnace roof



y 28, 1968 R. L. ALVIS ETAL ELECTRIC FURNACE ROOF Filed Feb. 4, 1966INVENTORS. Rober'f L. Alvis Roberf F. Cope/and John F Woo/er UnitedStates Patent 3,385,241 ELECTRIC FURNACE ROOF Robert L. Alvis and RobertP. Copeland, independence,

Mo., and John F. Wooler, Gibsonia, Pa., assignors to Geo. P. ReintjesCo., Inc., Jackson County, M0., a corporation of Missouri Filed Feb. 4,1966, Ser. No. 525,183 5 Claims. (Cl. 110-99) ABSTRACT OF THE DISCLOSUREA roof for an electric furnace which roof is normally horizontal in itsposition of use but which is tilted with the furnace when the furnace istapped, the roof having a peripheral element supported by the furnaceand a framework extending inwardly from the peripheral element andconnected to a central hub. The framework supports a brickwork archwhich has a central portion within the hub and a marginal portionbetween the hub and the peripheral element, the marginal portion beingsupported by a number of spaced members rigid to the framework, certainof the bricks of the marginal portion being suspended from said membersby hangers which engage the member and a loop carried by a correspondingbrick, the clearance between the loop and the member being limited sothat when the roof is tilted the bricks of the marginal portion arerestrained against any substantial shifting movement.

It is conventional in the electric furnace field to provide a removablebrick roof for the furnace, the roof being connected to a superstructureof a lifting mechanism whereby the superstructure and roof are swungaway from the furnace to permit top-charging of the latter, the roofthen being returned to its position atop the furnace for the heatingoperation. The electrodes for the furnace are carried by their ownlifting mechanism and are normally lifted and swung independently butare tilted with the roof and furnace.

When the furnace is ready for tapping, it is tilted as a unit with theroof, superstructure and electrodes to pour the molten metal from aspout located at the lower part of the furnace. The tilting operationnormally causes unusual stresses and distortions in the roof whichgreatly accelerate spalling and distintegration of the brickwork.Disintegration of the bricks is particularly a problem at the center ofthe roof as it receives a higher proportion of heat and consequently,the center fails before the useful life of the marginal bricks has beenfully realized. However, upon collapse of the central portion, themarginal portions of the self-supporting arch will also collapse,resulting in wasteful material loss.

The collapsing problem has been partially solved by constructing asectionalized roof such as shown in US. Patent No. 2,742,023, issued toGeorge P. Reintjes on Apr. 17, 1956. The sectionalized roof includesseparate supports for the central and marginal portions, but such a roofis not operable in conjunction with conventional lifting and tiltingequipment and, due to the expense of such equipment, industrial concernsare hesitant to discard the same. Also, the sectional roof requiresmodification of the furnace top and utilization of relatively expensive,non-standard bricks. Thus, the sectional roof method has not been apractical solution.

Accordingly, it is the primary object of this invention to provide aroof construction for electric furnace use wherein a conventionalself-supporting arch is utilized in conjunction with suspensionframework, the latter serving as an auxiliary support for the marginalportion of the arch after the center thereof collapses. Since a conven-3,385,241 Patented May 28, 1968 tional type arch is employed, the needfor modifying present roof lifting machinery is eliminated.Additionally, furnace modification will be unnecessary when using thepresent invention, and standard shapes of bricks may be utilized toobviate the excess cost necessitated by the unusual configurationsheretofore required.

An important object of this invention is to provide a roof of theaforementioned character wherein the stresses and distortions duringtapping are minimized by employing a framework assembly which rigidlysupports the arch. This is to be contrasted with many previoustechniques which utilized free suspension methods in an attempt to lowerinternal stresses within the arch.

Other objects include details of construction which will become apparentfrom the following specification and accompanying drawing, wherein:

FIGURE 1 is a top plan view of an electric furnace roof made pursuant tothe teachings of our invention, parts thereof being broken away toreveal details of construction;

FIG. 2 is a vertical, cross-sectional view thereof; and

FIG. 3 is an enlarged view similar to FIG. 2 showing the bricksuspension means in detail.

The roof of the present invention, broadly designated by the referencenumeral 10, is adapted for use with a cylindrical electric furnace, thelatter having an open top to present an upper peripheral edge forreceiving roof 10. Roof 10 includes an annular, peripheral skewback orroof ring element 12 having a generally triangular sleeve configurationto present a vertical leg 14, an inclined leg 16, and a horizontalflange 18. Normally, a water or air cooling passageway 20 is definedwithin ring 12 by legs 14 and 16 and flange 18. A plurality of brackets22 are secured to the outer face of vertical leg 14'and each has anaperture 24 formed therein for registering with complemental positioningpins provided at the top of the furnace.

Vertical leg 14 extends above inclined leg 16 and has a plurality ofclips 26 secured thereto at equally spaced points about ring 12. Eachclip 26 is rigidly secured to one end of a spoke 28 comprising an I-beamor similar member, the other end of the spoke being rigidly secured by astrap 30 to a hub or inner ring band 32 having a transversely U-shapedconfiguration and defining an opening 33 therewithin. Inner ring 32 isconcentric with roof ring 12 and vertically spaced therefrom by theframework of spokes 28.

A number of annular, concentric stringer members 34 are circumscribedabout inner ring 32 and are rigidly secured to the lower faces of spokes28 by brackets 36. Stringers 34 comprise fiat bars to present arectangular cross-sectional configuration.

Roof 10 is provided with a self-supporting brickwork sprung arch 38having a generally dome-shaped configuration. Arch 38 comprises aplurality of annular rows 40 of bricks 42, which rows 40 decrease indiameter as the center of the roof is approached. Bricks 42 are taperedin horizontal cross section so that the annular rows 41 can be formedwithout substantial gaps being presented between the bricks. There isgenerally asbestos or other compressible material 43 placed between thebricks to compensate for expansion and contraction of the brickwork.

The central portion 44 of arch 38 has three openings 46 formed thereinand defined by annular brick sleeves 48, there being refractory rammingmaterial 49 between sleeves 48 and bricks 42. Openings 46 are designedto receive the electrodes of the furnace therethrough. The particularlocation of inner ring 32 is determined by the location of openings 46and the electrode characteristics of the furnace as there should be nometal framework in terfering with the arching operation of theelectrodes. It

is common practice to space all metal framework at a distance of atleast 18 to 24 inches from the electrodes.

Arch 38 is normally constructed over a dome-shaped form with all of thebricks 42 being encased, with the casings 52 (shown in enlarged crosssection in FIG. 3) on the alternate rows 40 of the marginal portion 50of arch 38 being of the extended type having a loop 54 extendingupwardly therefrom. Arch 38 is self-supporting and is positioned in roofby resting the outer edge thereof on inclined leg 16 of roof ring 12,with spokes 28 and inner ring 32 then overlying arch 38;. Stringers 34are spaced to overlie the alternate encased rows of the marginal portion56 of arch 38 and are connected by hangers 56 to loops 54 of casings 52.Each hanger 56 includes a U- shaped hook 58 embracing the sides and topedge of a corresponding stringer 34, there being an integral re-benthook 66 provided on one of the legs of hook 58, hook 60 being insertedthrough the opening presented in loop 54.

In-operation, roof 10 is placed on the electrical furnace with flange 18of ring 12 lying on the upper peripheral edge of the furnace. Roof 10 isconnected to the superstructure of a conventional lifting and tiltingmechanism located adjacent the furnace. Each opening 46 has an electrodejournalled therethrough, which is carried by its own lifting mechanism,the electrodes and their mechanisms being arranged to tilt with thefurnace.

When it is desired to charge the furnace, the lifting mechanism isoperated to raise the superstructure, roof and electrodes as a unit, andswing the same away from the top of the furnace whereby the latter maybe charged. After charging, the roof is swung into overlyingrelationship with the furnace and lowered until apertures 24 of flanges22 register with the positioning pins provided adjacent the top edge ofthe furnace.

When the furnace is ready to tap, it is tilted as a unit with thesuperstructure, roof 10 and electrodes, and the molten material withinthe furnace is poured from a spout located near the bottom of thefurnace. The tilting operation imparts stresses and distortions to arch38 but the novel rigid framework suspension structure minimizes unusualpressures within the arch.

Particularly, the close proximity of stringers 34 to the loops 54 of thebricks carried thereby, as shown in FIG. 3, permits engagement of thestringers 34 with the loops 54 when the furnace is tilted therebyrestraining bricks 42 against any substantial shifting movement abouthook 60 as the furnace is tilted. This restraining or hold down actionexerted by the stringers 34 upon the bricks 42 of the marginal portions50 minimizes the stresses and dis tortions which would otherwise resultfrom frequent tilting of the roof and, therefore, prolongs the life ofbricks 42.

During prolonged use of roof 10, the central portion 44 of arch 38directly underlying the opening 33 defined by ring 32, will disintegrateat a higher rate than the marginal portion 50 which is suspended fromspokes 28. Thus, when central portion 44 has sufficiently disintegrated,it will collapse along with sleeves 48 and ramming material 49, butmarginal portion 50 will remain intact as it will then be carried byspokes 28 which thus serve as an auxiliary support to supplement theprimary support provided by the natural self-supporting structure of thearch. To refabricate the roof, it is only necessary to place the sameover a concrete form and replace the central portion 44 with new brickswhereby roof 10 may again be placed into service utilizing the olderbricks of marginal portion 50.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. A furnace roof comprising: a support having a peripheral element, ahub, and a framework interconnecting the element and the hub; aself-supporting brickwork arch within said element and carried therebyin spaced, underlying relationship to the hub and said framework, saidarch having a central portion and a marginal portion disposed betweenthe central portion and said element; and structure connecting theframework with at least certain of the bricks of said marginal portionfor suspending the latter from the support upon collapse of said centralportion and for restraining the bricks of said marginal portion upontilting of the furnace roof, said structure including a number of spacedmembers rigid to the framework over said marginal portion and means forconnecting said members with said certain bricks of the marginal portioncomprising one part carried by said certain bricks, said members andsaid one part being in sufficiently close proximity when the roof is ina horizontal position of use to restrain said certain bricks against anysubstantial shifting movement when the roof is tilted.

2. The invention of claim 1, said connecting means including a pluralityof hangers for each member respectively, each hanger having a hookengaging its corresponding member.

3. The invention of claim 2, each hanger having a second hook suspendinga corresponding brick therefrom.

4. The invention of claim 3, the one part being a loop carried by eachcorresponding brick, said second hook of each hanger being received bysaid loop.

5. The invention of claim 4, there being a limited clearance between thenormally uppermost portion of said loop and the normally lowermostportion of said member whereby when said roof is tilted said portionswill engage to restrain said certain bricks against any substantialshifting movement.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 120,383 12/1947Sweden.

FREDERICK KETTERER, Primary Examiner.

